The human polyomavirus, JCV, causes a demyelinating disease in immune compromised individuals, progressive multifocal leukoencephalopathy (PML). PML is a substantial neurological complication in AIDS patients, occuring in 8% of all cases. PML is the AIDS defining illness in almost 1% of AIDS cases. Although in the past PML was a rare disease, it now represents a large number of neurological disease and is considered on the increase by recent statistics from the CDC. JC Virus was originally thought to be strictly neurotropic, infecting only macroglial cells derived from the human brain. However, our results have now shown that there is a firm link between lymphoid and glial cells in the pathogenesis of JCV infection leading to demyelination in the human brain. We have identified the nucleotide sequences from the viral regulatory region which are 'signature' sequences in tonsil tissues, B lymphocytes in the tonsils, and stromal cells which make up the architecture of lymphoid organs. The data indicate that the same viral genotype which is found in brain tissue of PML patients originates from an initial lymphoid cell infection. The molecular similarities for JCV gene expression between cells of the nervous and immune systems directly correlated with the expression of the NF-1 class D family of DNA binding proteins which function for viral transcription. We have cloned the gene for NF-1/D from human brain which is highly expressed. There appears to be a close association between susceptibility of infection to JCV and expression of this DNA binding protein. We have made expression vectors for NF-1/D and produced cell lines which constituitively express NF-1/D. These cell lines are normally non-permissive for JCV transcription. However, we have converted them from non-permissive to permissive once selected for NF-1/D expression. We have extended this observation to both neural and lymphoid human progenitor cells in culture. For example, human CD34+ hematopoietic cells and human CNS stem cells are susceptible to JCV infection. However, monocytes differentiated from CD34+ cells and neurons differentiated from CNS stem cells are not susceptible to infection nor do these cells express competent levels of NF-1/D. We have also cloned and expressed the viral virion protein, VP1, which is responsible for cell attachment and entry of the viral particle. We have developed the methodology to allow the VP1 molecules to 'self-assemble' into icosahedron particles like a true virion particle. We add DNA of any origin into the self assembly process and can deliver genes to any cell type. We also use these viral like particles as antigens for the quantitation of antibody levels in the human population. We have determined that individuals, throughout the world, develop antibodies to JCV and the other human polyomavirus,BKV, which are not cross reacting nor able to limit viral reactivation leading to PML. We are also beginning to map the epitopes on the viral proteins responsible to antibody binding. We are collaborating with the FDA to re-examine the significance of the circulation of the primate polyomaviruses including JCV, BKV, and the monkey SV40, a contaminant in early human vaccines. Advancing technologies allows us to direct attention to possible therapies for PML in an increasing immune suppressed population. Currently we are the laboratory support for a clinical trial of intraparenchymal administration of ARA-C in AIDS patients with PML